Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria
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Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria A report for the Invasive Species Council | 10 June 2022
Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria 2
Final
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Contents
Overview 6
1 Introduction 9
1.1 Introduction 9
1.2 Understanding the costs of inaction requires an economic framework 10
1.3 Structure of this report 12
2 Context and background 13
2.1 Feral deer numbers in Victoria are rapidly increasing 13
2.2 In the absence of further action, feral deer numbers will continue to grow
16
2.3 Feral deer impose a range of economic, social, cultural and
environmental costs on the community 19
2.4 Management of feral deer to date, has been limited 22
2.5 The current approach is unlikely to be sufficient 23
3 Economic (incl. agricultural) impacts 24
3.1 The link between feral deer and economic outcomes 24
3.2 The agricultural cost of feral deer 28
3.3 Cost of reduced forestry production 31
3.4 The cost of increased likelihood of feral deer-related vehicle accidents 32
3.5 Accounting for uncertainty 34
4 Social and cultural impacts 36
4.1 The link between feral deer and social and cultural outcomes 36
4.2 The cost of feral deer on recreation opportunities in parks in Victoria 37
4.3 Accounting for uncertainty 39
5 The environmental cost of feral deer 41
5.1 The link between feral deer and environmental outcomes 41
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5.2 Estimating the environmental cost of feral deer 44
6 Results 46
6.1 The benefits of more substantive and sustainable feral deer
management could be significant 46
6.2 The unquantified impacts mean that the cost of feral deer may be higher
than estimated 48
6.3 The costs of acting quickly and decisively to remove feral deer will be
lower than the cost of feral deer on the community 49
Tables
Table 1: Range of forecast deer population by 2050 17
Table 2: Total agricultural cost of feral deer (PV terms, $2021-22, $millions) 29
Table 3: Total cost of lost forestry production (PV terms, $2021-22, $millions) 32
Table 4: Total cost of feral deer related accidents (PV terms, $2021-22, $millions) 34
Table 5: Economic cost of feral deer – results of the sensitivity and scenario analysis (PV terms,
$2021-22, $millions) 35
Table 6: Total social cost of feral deer (PV terms, $2021-22, $millions) 39
Table 7: Sensitivity analysis for social cost of feral deer (PV terms, $2021-22, $millions) 40
Figures
Figure 1: High-level overview of our approach 11
Figure 2: Deer population distribution in 2021 in Victoria, by species 15
Figure 3: Deer population distribution in 2021 in Victoria, by land use 15
Figure 4: Forecast feral deer numbers in Victoria 18
Figure 5: Exponential Growth of Population Size Over Time 19
Figure 6: Overview of the economic, social, cultural and environmental costs of feral deer in
Victoria 21
Figure 7: How feral deer impact economic outcomes 26
Figure 8: Feral deer population distribution in 2021 in Victoria, by land use 28
Figure 9: Approach to valuing the agricultural cost of lost grazing caused by feral deer 30
Figure 10: Approach to valuing the agricultural cost of time spent managing feral deer 30
Figure 11: Approach to valuing lost forestry production 32
Figure 12: Forecast number of feral deer-related accidents per year 33
Figure 13: Approach to valuing feral deer-related accidents per year 34
Figure 14: How feral deer impact social and cultural outcomes 37
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Figure 15: Calculating the value of lost recreational opportunities from managing feral deer 38
Figure 16: How feral deer impact environmental outcomes 42
Figure 17: Impacts of feral deer on peatlands and bogs in Alpine National Park, Victoria 43
Figure 18: Feral deer wallow Warrandyte 44
Figure 19: Economic, social, cultural and environmental costs of feral deer in Victoria over the
period to 2051 ($millions, $2020-21, PV terms) 47
Figure 20: Sensitivity analysis: Economic, social, cultural and environmental benefits associated
with feral deer management in Victoria over the period to 2051 ($millions, $2020-21) 48
Boxes
: Applying benefit transfer to value key economic, social, cultural and environmental impacts
of feral deer in Victoria 12
: Types of feral deer in Victoria 14
: Our approach to forecasting feral deer numbers in Victoria 17
: Stakeholder feedback – population forecasts and carrying capacity 19
: Current legal status of deer 23
: Summary of stakeholder engagement – economic cost of feral deer 27
: Understanding the recreational cost of feral deer 39
: Summary of stakeholder engagement – environmental cost of feral deer 42
: Understanding the environmental cost of feral deer 45
: Indicative cost of removing feral deer 50
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Overview
In recent years the Victorian feral deer population and distribution have rapidly increased with
analysis by the Victorian Department of Environment, Land, Water and Planning (‘DELWP’)
suggesting that the population of deer could be between “several hundred thousand up to one
million wild animals or more”1. The dramatic increase is partially a result of the current legal status
of deer,2 which makes it difficult undertake strategic, large-scale management.
The challenge in managing feral deer is likely to be exacerbated in future, with populations
expected to increase significantly over the next thirty years, driven by a combination of climate
change, natural dispersal and deliberate releases and farm escapes. 3 Our analysis estimates that
even under conservative assumptions, if no significant management action is taken, by 2050
there could be 1.7 to 4.6 million feral deer in Victoria. 4
While the number of deer in future is uncertain, what is known is the significant economic, social,
cultural, and environmental cost imposed by feral deer on the Victorian community. 5
The benefits of more substantive and sustainable feral deer management in
Victoria could be significant
Frontier Economics was engaged by the Invasive Species Council to examine the economics of
managing feral deer in Victoria. As part of this analysis we have identified, and where possible,
valued the economic, social, cultural and environmental impacts on society of failing to manage
feral deer to an ecologically sustainably level (i.e. at a level at which they are likely to have limited
negative impact on the economic, social, cultural and environmental outcomes in Victoria). To the
extent that controlling the feral deer population saves economic, social, cultural and
environmental costs, these are considered to be an economic benefit arising from the controls.
1
Estimate as of October 2020. See: Department of Environment, Land, Water and Planning (2020), Victorian Deer
Strategy, 9. Note, this population estimate has not changed since the 2018 draft of the Strategy.
2
Under the current legislative framework, authorisation under the Wildlife Act is required to control deer on
Crown land every time management is to occur.
3
Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
4
It should be noted that this analysis does not seek to definitively forecast future feral deer numbers in Victoria.
Rather, we have sought to provide an indication of the range of potential feral deer numbers based on advice
from subject matter experts, to help decision-makers understand the possible cost on the community as a
result of inaction.
5
See for example Davis et al (2016) ‘A systematic review of the impacts and management of introduced deer
(family Cervidae) in Australia’ Wildlife Research 43, 515-532; Lindeman, M.J and Forsyth, D.M (2008) ‘Agricultural
impacts of wild deer in Victoria’, Arthur Rylah Institute for Environmental Research, Technical Report Series No.
182, Victorian Department of Sustainability and Environment; Environment and Communications Reference
Committee, Parliament of Australia, Impact of feral deer, pigs and goats in Australia (2021); Claridge, A.W (2016)
Synopsis of perceptions about introduced deer among park management ranger staff across the Australian
Alps, NSW National Parks and Wildlife Service; Cripps, J (2019) ‘Introduced deer and their potential role in
disease transmission to livestock in Australia’ Mammal Review 49, 60-77.
Frontier Economics 6Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final Drawing on the best available information, our analysis indicates that the cost to the broader community of feral deer could be over $1.5bn (7% discount rate) or $2.2bn (4% discount rate) in present value (PV) terms, over the next 30 years. This estimate is made up of: • $245m to $350m in economic costs from lost gross margin due to grazing (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes 10% of the feral deer population are grazing on farmland, which reduces the opportunity to fully stock that land for grazing, resulting in a reduction in income for the farmer. • $106m to $144m in economic costs from resources spent managing feral deer (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes a farmer spends 20 days a year managing feral deer on their properties. • $269m to $365m in economic costs from lost forestry production (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes a reduction in production of plantations as a result of feral deer grazing and trampling through the forests. • $576m to $825m in economic costs from deer-related vehicle accidents (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This assumes that all future feral deer related crashes on highways within Victoria can be avoided. • $308m to $474m in social costs from reduced recreation and use values (in PV terms, over the next 30 years, 7% and 4% discount rate, respectively). This is based on the assumption that uses of Victorian national and state parks for recreation will be dampened by 1% due to the impact of feral deer. The unquantified impacts mean that the cost of feral deer may be higher than estimated Although our analysis has sought to value the benefits (including cost savings) associated with managing feral deer in Victoria, given the availability of information these figures do not capture the full range of potentially significant costs of feral deer in Victoria. These include the impact of feral deer on: • the other costs of management • the cost of water supply • the risk of disease • indigenous cultural heritage • biodiversity • the health of rivers and waterways As such, it is likely that the true economic, social, cultural and environmental costs imposed on the community as a result of feral deer in Victoria are larger than our estimate. Understanding the change in outcomes and the appropriate price is critical to robustly value the economic, social, cultural and environmental benefits of managing feral deer within Victoria. Given the significant impact of feral deer in Victoria, there is likely to be benefit in undertaking further work to better understand the magnitude of the problem, and therefore, the benefits of action. Frontier Economics 7
Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
Decisive action is required
While there are costs associated with reducing feral deer numbers to sustainable levels, these
are unlikely to outweigh the benefits of control. Our analysis suggests that if management is
taken in 2022, the cost of removing all feral deer could be between $338m and $581m
(depending on the population scenario).6 This cost would have to rise by around four times
before the conservatively estimated benefits of controlling deer was outweighed. Having said
this, we acknowledge that both the extent and approach to feral deer management will
determine the level of benefits society receives, because different management strategies will
have different impacts on the feral deer population, at different costs.
Our findings highlight the need for decisive action to manage the feral deer population in
Victoria. The longer control is delayed the larger the population of feral deer and the greater the
cost of inaction. In other words, a strategy that quickly and significantly reduces deer numbers
will deliver greater benefits than a slower response, while at the same time requiring lower costs
to achieve
These results are inherently uncertain and there are gaps in the available research and primary
data on the impacts of specific feral deer in Victoria. However, even if these uncertainties could
be resolved with more research, given the conservative approach we have taken, improved
information is more likely to increase the benefits of control, thereby reinforcing the conclusion
that controlling feral deer is net beneficial.
6
Uncertainty around the number and distribution of feral deer in Victoria makes it difficult to quantify the exact
cost of the feral deer management in Victoria. The marginal cost of removing feral deer is greatly dependent on
the location, density of feral deer, and management technique and some management methods are not
suitable for some areas of Victoria. That being said, analysis by the Invasive Species Council estimate the
average cost of removal to be $404 per deer based on assumed effectiveness of aerial shooting.
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1 Introduction
Key points
• In recent years the Victorian feral deer population and distribution have rapidly
increased.
• While there is broad recognition that feral deer can impose a variety of economic, social,
cultural and environmental costs on the community, the impacts of feral deer in Victoria
have not been well-quantified, hindering decision-makers ability to make informed
decisions about feral deer control.
• Frontier Economics was engaged by the Invasive Species Council to examine the
economics of managing feral deer in Victoria. As part of this analysis we have identified,
and where possible, valued the economic, social, cultural and environmental impacts on
society of failing to manage feral deer to an ecologically sustainable level.
• Our analysis has not sought to value all economic, social, cultural and environmental
costs imposed by feral deer. Given the data and time constraints we have focused on
those impacts that are likely to be most material. Should information become available
to enable the quantification and valuation of other economic costs, this will most likely
strengthen the case for decisive action as we have used costs at the lower of the likely
range.
1.1 Introduction
In recent years the Victorian deer population and distribution have rapidly increased 7 with
analysis by the Victorian Department of Environment, Land, Water and Planning (‘DELWP’)
suggesting that the population of deer could be between “several hundred thousand up to one
million wild animals or more”.8
While there is broad recognition that feral deer can impose a variety of economic, social, cultural
and environmental costs on the community, the impacts of feral deer in Victoria have not been
well-quantified, hindering decision-makers ability to make informed decisions about feral deer
control.
To make more informed decisions about the nature and extent of any intervention to manage
feral deer in Victoria, it is critical to understand all the cost and benefits that arise from an
intervention or conversely, inaction. This should include social, environmental and economic
impacts. Converting the full range of cost and benefits imposed on the community 9 into dollar
7
See for example, the Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
8
Estimate as of October 2020. See: Department of Environment, Land, Water and Planning (2020), Victorian Deer
Strategy, 9. Note, this population estimate has not changed since the 2018 draft of the Strategy.
9
This includes the local, broader Victorian and Australian communities.
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values10 can help decision makers compare feral deer management options and assist them to
determine whether and how to act.
When the broad range of social, environmental and economic impacts of feral deer in Victoria are
not considered or monetised there is a risk that these impacts will be ignored. This can lead to
suboptimal management outcomes.
Against this background, Frontier Economics was engaged by the Invasive Species Council to
examine the economics of managing feral deer in Victoria. As part of this analysis we have
identified, and where possible,11 valued the economic, social, cultural and environmental impacts
on society of failing to manage feral deer to an ecologically sustainably level (i.e. at a level at
which they are likely to have limited impact on the economic, social, cultural and environmental
outcomes in Victoria).
1.2 Understanding the costs of inaction requires an economic
framework
As shown in Figure 1, our approach involved six key steps:
1. Forecasting future deer numbers over the period from 2022 to 2051. This was a function
of four inputs: starting population, growth rate (which includes loss from death and shooting),
carrying capacity per hectare (K), and location/ area of deer habitat.
2. Reviewing existing literature examining the impact of feral deer in Victoria on
economic, social, cultural and environmental outcomes. This includes:
• use-values – these accrue to users, for example, land-holders, visitors to parks etc.
• non-use values – these values arise from the knowledge that the Victorian environment
(including its habitats and the species it supports) exist and will continue to exist. They are
different from use values because they arise whether or not the environment or park is
used and as such, can be attributed to the population beyond just those who use and visit
the area (e.g. the broader Victorian community).
3. Identifying the change in economic, social, cultural and environmental outcomes that
could arise as a result of feral deer in Victoria, over the period from 2022 to 2051.
10
Note all figures in the report are $2021-22. Some figures are presented on a per year basis. Others are
presented as present value figures, in line with Victoria Department of Treasury and Finance (DTF) guidance,
which requires costs and benefits to be discount using a social discount rate. We have adopted a discount rate
of 4% and 7%, consistent with DTF guidelines (The Victorian DTF recommends the use of the social discount rate
of 4% for Category 1 projects and 7% for Category 2 projects) See DTF (2013), Economic Evaluation for Business
Cases Technical Guidelines.
11
As discussed in more detail below, there is limited scientific and economic data available on the specific impacts
of alternative feral deer management approaches in Victoria. Our analysis makes reasonable, conservative
assumptions where required in a data poor environment, and we have articulated caveats to the analysis as
appropriate. Where quantification isn’t possible with available data, we have undertaken a qualitative
assessment of these impacts using case studies and other available evidence.
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4. Valuing the key costs associated with failing to manage feral deer in Victoria. At a high
level, this involves multiplying the change in outcomes from step 3 by the appropriate price
and discounting the costs using the social discount rate of 4% and 7%.12
Given the timeframe available for this analysis we have adopted a benefit transfer approach
(see Box 1). This involves drawing on existing literature to value impacts (and making any
necessary adjustments to reflect the Victorian context), rather than undertaking primary
research.
5. Understand how the cost of feral deer vary under alternative states of the world, for
example under alternative future deer population scenarios.
6. Identifying, at a high level, the cost associated with management approaches (i.e. the
financial cost of aerial shooting of feral deer)
Figure 1: High-level overview of our approach
Source: Frontier Economics
Each step has been supported by ongoing consultation with key stakeholders and subject matter
experts. This included engagement with Victorian Government and Non-Government
organisations, businesses, landholders and academics. For example, we held 3 workshops in
April 2022 and a range of individual discussions with key stakeholders over 2021 and 2022 to
assist in our understanding of the issues, and test assumptions and analysis. We have included
the feedback we received from these sessions in this analysis.
Importantly, our analysis has not sought to value all economic, social, cultural and environmental
costs of feral deer, rather, given data and time constraints, we have focused on those likely to be
most material and where data is readily available. Should information become available to
enable the quantification and valuation of other economic costs, this will likely strengthen the
case for decisive action.
12
The Victorian Department of Treasury and Finance recommends the use of the social discount rate of 4% for
Category 1 projects and 7% for Category 2 projects. See DTF (2013), Economic Evaluation for Business Cases
Technical Guidelines.
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: Applying benefit transfer to value key economic, social, cultural and environmental
impacts of feral deer in Victoria
Benefit transfer involves using values estimated in a source study and transferring these for
use in the case of interest. For this approach to be valid, the following conditions need to be
satisfied:
• The source study should be rigorous and valid
• The context and conditions pertaining in the case of interest should be similar to those
occurring in the source study.
• The demographic and economic characteristics of any sampled population sampled in
the source study should be similar to those in the target study.
• The extent of the changes being investigated should be similar.
A benefit of this approach is that as does not require original empirical study (scientific,
survey, econometric, or other) design and execution, benefit transfer can be rapidly applied.
However, the applicability will be limited to outcomes with a large body of research (where
the original research is robust and the study sites are sufficiently similar) and, in this case,
there are very few applicable primary studies that are well suited for use, particularly around
the specific environmental impacts of feral deer in Victoria.
Source: Frontier Economics
1.3 Structure of this report
The remainder of this report is structured as follows:
• Section 2 provides an outline of the context and background of this analysis.
• Section 3 provides an overview of agricultural impacts of feral deer.
• Section 4 summarises the social impacts of feral deer.
• Section 5 provides an overview of the environmental impacts of feral deer.
• Section 6 provides a summary of our key findings and results
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2 Context and background
Key points
• In recent years the Victorian feral deer population and distribution have rapidly
increased. Our analysis suggests that feral deer numbers could grow to between 1.7
million to 4.6 million by 2050, an increase of between 103% and 217% over the next 30
years.
• While historically, the impacts of feral deer in Victoria have not been well quantified,
research suggests that feral deer within Victoria have had a significant detrimental
impact on a range of economic, social, cultural and environmental outcomes.
• Despite recognition of the damage caused by feral deer in Victoria, management to date
has been limited. Historical approaches to management have been relatively reactive
and uncoordinated, where feral deer management is undertaken to address specific
issues in localised areas.
• While the number of feral deer in future is uncertain, what is clear is that decisive action
is required to mitigate the potentially significant cost of feral deer in Victoria.
2.1 Feral deer numbers in Victoria are rapidly increasing
Up until the 1980s, it was relatively rare to see a deer in the wild. However, in recent years the
Victorian deer population and distribution have rapidly increased 13 with analysis by DELWP
suggesting that the population of deer could be between “several hundred thousand up to one
million wild animals or more”.14
As discussed in Box 2, four species of deer have established populations in the wild in Victoria:
Sambar, Fallow, Hog and Red Deer.15
13
See for example, the Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
14
Estimate as of October 2020. See: Department of Environment, Land, Water and Planning (2020), Victorian Deer
Strategy, 9. Note, this population estimate has not changed since the 2018 draft of the Strategy.
15
Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
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: Types of feral deer in Victoria
Four species of feral deer have established populations in the wild in Victoria:
• Fallow Deer (Dam dama), have a patchy distribution across Victoria and have
historically existed in low numbers within most occupied areas.
• Red Deer (Cervus elaphus), as with Fallow Deer, the distribution of Red Deer is fairly
patchy across Victoria. For example, the largest population of Red Deer in Victoria is
located within the Grampians National Park, and consists of between 300 and 500 deer.
• Hog Deer (Axis porcinus), have a limited distribution and are found in coastal areas of
Gippsland, including Wilsons Promontory National Park and Nooramunga Marine and
Coastal Reserve.
• Sambar Deer (Cervus unicolor), which are the most prevalent and widespread species
of deer in Victoria, occurring over most of eastern Victoria, French Island and at
Timboon in the south west. Recent reports indicate that Sambar Deer may be found in
and around the Grampians.
Another two deer species, Chital Deer (Axis axis) and Rusa Deer (Cervus timorensis), were
also released in Victoria but are mostly found on farms (although they have been
successfully established in other Australian states, including New South Wales).
Source: Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
Studies have also suggested that the population is becoming more dispersed, with feral deer
becoming an increasing problem for private and public landholders across Victoria. Deer can
inhabit many different habitat types from dense forest, rough mountainous terrain and alpine
environments to more open-country including semi-open scrublands, pine plantations and open
grazing land.16
While historically feral deer were predominantly found in East and North East Victoria, as shown
in Figure 2 and Figure 3, they have begun to spread beyond national and state parks and forests
to land that is used for productive purposes (including dryland and irrigated agriculture and
plantations) and ss noted by the Victorian Deer Strategy, there is potential for further spread. 17
16
We note that different species are more suitable to different habitats with Fallow deer more likely to spend time
on grazing land, and Sambar are more likely to be in forested areas.
17
Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
Frontier Economics 14Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final Figure 2: Deer population distribution in 2021 in Victoria, by species Source: Frontier Economics using DELWP data. This data is sourced using anecdotal and observational evidence from landholders, community groups and park rangers along with data from the DeerScan app. Figure 3: Deer population distribution in 2021 in Victoria, by land use Source: Frontier Economics using DELWP and ABARES data. This data is sourced using anecdotal and observational evidence from landholders, community groups and park rangers along with data from the DeerScan app. Note: The legend reflects ABAREs classification Frontier Economics 15
Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
2.2 In the absence of further action, feral deer numbers will
continue to grow
The challenge in managing feral deer is likely to be exacerbated in future, with populations
expected to increase significantly over the next thirty years, driven by a combination of climate
change, natural dispersal and deliberate releases and farm escapes. 18 While there is uncertainty
around the exact number of deer today and in future (given the lack of analysis of total deer
numbers in Victoria or site specific densities), a range of studies around Australia have
investigated aspects of deer populations. These include:
• Watter et al estimated that the annual population growth rate of Sambar deer is between
15%-24% per year based on observed reproductive patterns of the species in Victoria, which
accounts for biological factors such as estimated fecundity rate, as well as deaths due to
predation and recreational hunting.19
• Letherbridge et al and Cunningham et al estimated the growth rate of fallow deer in Tasmania
to be between 5.4% and 11.5% per year (accounting for management and hunting). 20
We note that other studies (for example) have estimated the unconstrained estimated the
maximum annual population growth rate (i.e. population growth in an environment with no
competition for food, no predation and no other external threats). For example, Hone et al
estimated the unconstrained population growth to be of feral deer in Victoria to be between 45%
and 85% depending on the deer type.21
Drawing on publicly available literature and advice from key stakeholders and experts (such as
DELWP and Parks Victoria), our analysis has attempted to forecast the future deer population in
Victoria (see Box 3 for further information on the assumptions behind the forecast). Given the
uncertainty around the future growth rate, as shown in Figure 4 our analysis includes a spectrum
of future deer population numbers:
• Low population forecast of 1.7 million deer by 2050
• Medium population forecast of 3.1 million deer by 2050
• High population forecast of 4.6 million deer by 2050
18
Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
19
Watter, K, White, N, Finch, N and Murray, P.J. (2020) ‘Reproductive seasonality and rate of increase of wild
sambar deer (Rusa unicolor) in a new environment, Victoria, Australia’, Animal Reproductive Science 23.
20
Ibid. See also Cunningham et al (2021) ‘Dynamics and predicted distribution of an irrupting ‘sleeper’ population:
fallow deer in Tasmania’, Biological Invasions.
21
In particular, the study found the maximum annual population growth for Sambar deer to be 55%, Hog deer to
be 85% and Fallow deer to be 45%. Hone, J, Duncan, R.P, Forsyth, D.M (2010) ‘Estimates of maximum annual
population growth rates of mammals and their application in wildlife management’, Journal of Applied Ecology 47,
507-14, 511.
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: Our approach to forecasting feral deer numbers in Victoria
Our forecast is a function of four inputs:
• Starting population
• Growth rate accounting for loss from death and shooting
• Carrying capacity per hectare (K)
• Location/ area of deer habitat
We have assumed that across time the population of deer will grow at a low density and
disperse across a larger area, or it will grow within a confined area, with a high density. We
note that this does not cover the range of possibilities of population dispersal and density
patterns. However, we have included this assumption as an attempt to account for these
complex dynamics across our different scenarios.
Under the medium estimate we assume that the deer remain where they are found now
and grow to a high density and spread at a lower density across potential habitable areas
in Victoria.
Table 1: Range of forecast deer population by 2050
Assumption Low estimate Medium estimate High estimate
Starting population 750,000 1,000,000 1,250,000
Growth rate
accounting for loss
11.5% 13.25% 15%
due to death and
shooting
0.2
Carrying capacity
0.2 + 0.2
per hectare (K)
0.1
8 million hectares
Location/ area of 22.8 million
8 million hectares +
deer habitat hectares
14 million hectares
Forecast deer
1.7 million 3.1 million 4.6 million
population by 2050
Source: Frontier Economics analysis
Note: to ensure robustness we consulted with the Invasive Species Council, DELWP, Parks Victoria, Arthur Rylah Institute
and other key stakeholders about these forecasts
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Figure 4: Forecast feral deer numbers in Victoria
Source: Frontier Economics based on advice from the Invasive Species Council and key stakeholders
We understand that in practice there is likely to be large variation in population dynamics across
time (including the covid impact on shooting and bushfire impacts) and there is a complex
relationship between carrying capacity and deer population numbers (as discussed in Box 4).22 In
addition, there is uncertain around potential deer habitat in Victoria.
As such, it should be noted that this analysis does not seek to definitively forecast future
deer numbers in Victoria. Rather, we have sought to provide an indication of the range of
potential deer numbers to help decision-makers understand the possible cost on the
community as a result of inaction.
While the number of feral deer in future is uncertain, what is known is that decisive action is
required to address feral deer in Victoria.
22
Stakeholder feedback was provided to Frontier Economics and the Invasive Species Council as part of a range of
workshops in April 2022 and individual consultation throughout 2021 and 2022.
Frontier Economics 18Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
: Stakeholder feedback – population forecasts and carrying capacity
We note that in practice, deer population will not flatline around the carrying capacity. For
example, the 2019-20 bushfires resulted in a decline in the feral deer population in Victoria.
However, six to twelve months after the fires, the feral deer population increased again, as
habitat and food availability increased. That is, in practice, the feral deer population
fluctuates around the carrying capacity, as per Figure 5.
Figure 5: Exponential Growth of Population Size Over Time
Source: Frontier Economics based on information from https://ecocity.partners/2020/03/26/carrying-capacity-viral-media-
and-the-logarithmic-scale/
However, given data availability we have adopted a simplified representation of this
relationship to provide an indication of the range of potential deer numbers to help decision-
makers understand the possible cost on the community as a result of inaction.
While stakeholders noted that, in practice, deer population would not flatline around the
carrying capacity, there was a consensus across all workshops that the population of deer
are expected to increase.
Source: Frontier Economics informed by key stakeholders
2.3 Feral deer impose a range of economic, social, cultural and
environmental costs on the community
Historically, the impacts of feral deer in Victoria have not been well-quantified, however, they are
believed to be significant and increasing in their extent and severity, as the population grows. 23 In
23
Department of Environment, Land, Water and Planning (2020), Victorian Deer Strategy
Frontier Economics 19Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
particular, as shown in Figure 6, research suggests that feral deer within Victoria have had a
significant detrimental impact on a range of economic, social, cultural and environmental
outcomes (compared to an ecologically sustainable level of deer).24 These include25:
• Economic-related costs, such as:
o Cost to the agricultural sector:
Damage to crops (such as cereal, nut and fruit orchards, vegetables, vineyards and
plantations) and other primary production, such as fouling of pasture. 26
Cost to landholders of managing feral deer, such as the cost of ground shooting, fencing
the property or replacing damaged property.
Competition with livestock for grazing.
Risk of disease as deer can transmit diseases to livestock (e.g. cattle and sheep)
o Reduced forestry production - Reports suggest that deer significantly reduce the quality
and total volume of timber produced by Victoria’s forestry industry, primarily as a result of
browsing and bark-stripping.27
o Deer-related vehicle accidents (including fatalities, accidents and vehicle-only damage)
o Cost of managing deer by other parties, including the Victorian Government
o Cost of water supply, as a result of increased treatment requirements. Melbourne
Water has suggested that failure to adequately control deer in the water catchments, could
result in the need to build costly water-treatment infrastructure to meet water quality
standards.28
• Environmental-related costs, such as:
o Negative impact on biodiversity, including spreading weeds, trampling understory,
stripping and ring barking (as a result of rubbing antlers on trees), impacting the
effectiveness of ecological restoration work and competing with native wildlife for food.
24
See for example Davis et al (2016) ‘A systematic review of the impacts and management of introduced deer
(family Cervidae) in Australia’ Wildlife Research 43, 515-532; Lindeman, M.J and Forsyth, D.M (2008) ‘Agricultural
impacts of wild deer in Victoria’, Arthur Rylah Institute for Environmental Research, Technical Report Series No.
182, Victorian Department of Sustainability and Environment; Environment and Communications Reference
Committee, Parliament of Australia, Impact of feral deer, pigs and goats in Australia (2021); Claridge, A.W (2016)
Synopsis of perceptions about introduced deer among park management ranger staff across the Australian
Alps, NSW National Parks and Wildlife Service; Cripps, J (2019) ‘Introduced deer and their potential role in
disease transmission to livestock in Australia’ Mammal Review 49, 60-77.
25
We note that Sambar, Red Fallow and Hog Deer have slightly different impacts due to differences in diet, size
and habitat preferences. However, given the strategic nature of this report, and the lack of species-specific
forecasts in Victoria, in this analysis, we discuss the impacts of deer as a whole.
26
A survey conducted by the Invasive Species Council of North East Victorian landholders found that 42% of
respondents reported costs associated with damage to pasture, crops and trees.
27
Ward, A, White, P, Smith, A and Critchley, C (2004) ‘Modelling the cost of roe deer browsing damage to forestry’
Forestry Ecology and Management 191, 301-310. See also; Reimoser, F, Armstrong, H, Suchant, R (1999)
‘Measuring forest damage of ungulates: what should be considered’ Forest Ecology and Management 120, 47-58.
28
GHD (2020), Combatting the impact of feral deer on Melbourne’s protected water catchments, available at:
https://www.ghd.com/en/perspectives/combating-the-impact-of-feral-deer-on-melbourne-s-protected-water-
catchments.aspx
Frontier Economics 20Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
This is likely to be exacerbated in fire-effected areas, where the presence of deer has
impeded regrowth and regeneration.
o Reduced health of rivers and waterways, through grazing, localised soil compaction and
erosion.
• Social-related costs, such the impact on amenity and recreation opportunities in
national and local parks, including:
o Reduced opportunity for, and amenity of, active recreation (e.g. hiking and cycling) as
a result of erosion of paths, increased deer-related accidents (e.g. hikers and cyclists feel
less safe when they encounter large animals)
o Reduced amenity associated with passive recreation (e.g. sightseeing and tours in
parks) as a result of the degradation of the natural environment, such that parks have a
lower aesthetic value.
o Risk of disease – Deer can transmit diseases (such as cryptosporidiosis, neosporosis and
leptospirosis) to humans, livestock and other animals and can lead to serious economic
and social impacts.
o Impact on indigenous cultural heritage, including soil compaction and erosion, damage
to native plant species and competition with native species for grazing in grassy, shrubby
and herb-rich woodlands.
Figure 6: Overview of the economic, social, cultural and environmental costs of feral deer in
Victoria
Source: Frontier Economics
Critically, these impacts are not restricted to the state of Victoria, with modelling suggesting that
dispersal of deer in the landscape is contiguous across the state borders with South Australia and
New South Wales.
Frontier Economics 21Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
2.4 Management of feral deer to date, has been limited
Despite recognition of the damage caused by feral deer in Victoria, management to date has been
limited, with present day hunting referred to only “a drop in the ocean” during stakeholder
engagement.29 Stakeholder feedback noted that historical approaches to management have been
relatively reactive and uncoordinated, where feral deer management is undertaken to address
specific issues in localised areas.
In particular, rather than a large-scale, strategic approach to the management of feral deer, the
existing management strategy relies heavily on a combination of Government intervention and
private hunting:
Ground shooting: The primary control method for deer is shooting, which is carried out by
professional shooters, accredited volunteer hunters, commercial harvesters, and recreational
hunters. Chital, Fallow, Hog, Red, Rusa and Sambar Deer are currently declared as ‘game’
under the Wildlife Act which allows them to be hunted by licensed recreational hunters. Deer
hunting is a valued recreational activity undertaken by more than 38,000 licensed hunters
across Victoria.30 For example, in 2019 private hunting resulted in the harvesting of 173,784
feral deer in Victoria, a significant increase compared to 2009.31 We note that this number is
uncertain, with stakeholder feedback suggesting that the number could be much higher.32
• Aerial shooting - Aerial shooting is being used to deliver deer control in accessible and
remote terrain where ground shooting is impractical. This is growing in use as management
strategies adopt a combination of ground and aerial shooting.
• Exclusion fencing - Exclusion fencing is currently used by farmers to exclude deer from
browsing and grazing on crops and pastures, and to protect some specific environmental
values. For example, exclusion fencing is used in the Alpine National Park on the Bogong High
Plains to protect threatened species and at Mount Bullfight to protect Alpine Tree Frog
(threatened under the FFG Act) habitat. While deer fencing provides a long-term solution, it is
only applicable to relatively small areas.
• Trapping (though it is not commonly adopted).
The approach to management is likely to be partially driven by the current legal status of deer,
which makes it difficult undertake strategic, large-scale management. As discussed in Box 5, under
the current legislative framework, authorisation under the Wildlife Act is required to control deer
on Crown land every time management is to occur.
29
Stakeholder feedback was provided to Frontier Economics and the Invasive Species Council as part of a range of
workshops in April 2022.
30
Deer can be hunted in State forest, certain forest parks (Cobboboonee and Otway) and other unoccupied Crown
land (such as Crown land that is not leased or licensed), leased Crown land (with permission of the lessee),
licensed Crown land, some state game reserves and private land (with permission of the landowner/manager).
Deer can also be hunted in some National, State, Coastal and Wilderness Parks, subject to varying conditions.
31
Moloney, P.D. and Hampton, J.O. (2020). Estimates of the 2019 deer harvest in Victoria: results from surveys of
Victorian Game Licence holders in 2019. Unpublished Client Report for the Game Management Authority. Arthur
Rylah Institute for Environmental Research, Department of Environment, Land, Water and Planning, Heidelberg,
Victoria.
32
Stakeholder feedback was provided to Frontier Economics and the Invasive Species Council as part of a range of
workshops in April 2022.
Frontier Economics 22Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
: Current legal status of deer
While deer are protected wildlife under the Wildlife Act 1975, the extent to which they can
be managed varies significantly depending on whether the land is in private or public
ownership.
• Private ownership – On private land deer are unprotected by an order of Governor in
council, which enables the conditional control of deer where they are causing damage
(without a permit)
• Public ownership - Deer control on public land requires authorisation by DELWP under
the Wildlife Act.
Source: Invasive Species Council
While this analysis does not purport to identify the appropriate approach to managing feral deer,
we note that there are other management strategies which have yet to be implemented in
Victoria, but have been considered in literature and other states, such as baiting and biological
control methods.
2.5 The current approach is unlikely to be sufficient
While efforts are being made to remove deer from Victoria through varying public and private
management techniques, this is insufficient to abate current and projected growth in population
numbers. For example, the Victorian National Parks Association noted recreational hunting
cannot be relied on as an effective management strategy as:
“…Victoria] has reached a point where population increases far exceed any huntable amount and
partly because amateur hunting is unstrategic [and only] randomly reduc[es] deer numbers in easily
accessible areas.”33
In 2020 the Victorian Deer Control Strategy was released after several years in development. This
strategy is a key action under the Victorian Government’s Sustainable Hunting Action Plan 2016-
2020. During the strategy development process, there was significant pressure exerted by the
community to change the legal status of deer from “protected wildlife” to that of a “pest animal”,
to appropriately recognise the population explosion and serious impacts across Victoria.
However, deer remain protected under the Wildlife Act 1975. This decision affords deer a level of
protection which restricts the ability to effectively manage the growing population.
Given this, further action is likely to be required to manage reduce the rapid increase of feral
deer in Victoria.
33
Victorian National Parks Association (2018), Dealing with deer, available at
Frontier Economics 23Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
3 Economic (incl. agricultural) impacts
Key points
• Various studies and anecdotal evidence have found a link between the presence of feral
deer in Victoria and a range of economic costs, including costs to the agricultural and
forestry sectors, vehicle accidents, management costs and costs related to water supply.
• Our analysis has estimated the economic cost of feral deer to be between $1,197m (7%
discount rate) and $1,684m (4% discount rate) (in present value terms, over the period
to 2051), comprised of:
o $245 to $350m in costs from lost gross margin due to grazing (7% and 4% discount
rate respectively)
o $106m to $144m in costs from days spent managing feral deer (7% and 4% discount
rate respectively)
o $269m to $365m in cost from lost forestry production (7% and 4% discount rate
respectively)
o $576m to $825m in costs from deer-related vehicle accidents (7% and 4% discount
rate respectively).
• Given the availability of information we have sought to include other costs of managing
feral deer and the cost of feral deer on water supply in our analysis qualitatively.
3.1 The link between feral deer and economic outcomes
Various studies and anecdotal evidence (see Box 6) have found a link between the presence of
feral deer in Victoria and a range of economic costs34 As shown in Figure 7, these include:
• Costs to the agricultural sector, including:
o Damage to crops (such as cereal, nut fruit and vegetables, vineyards and plantations) and
other primary production, such as fouling of pasture.
34
See for example, Lindeman, M.J and Forsyth, D.M (2008) ‘Agricultural impacts of wild deer in Victoria’, Arthur
Rylah Institute for Environmental Research, Technical Report Series No. 182, Victorian Department of
Sustainability and Environment; Environment and Communications Reference Committee, Parliament of
Australia , Impact of feral deer, pigs and goats in Australia (2021); Stenekes N, Kancans, R and Binks B (2017)
‘Pest animal and weed management survey: national landholder survey results’ Australian Bureau of Agricultural
and Resource Economics and Sciences, Department of Agriculture, Canberra; Claridge, A.W (2016) Ecological and
agricultural impacts of introduced deer in the Australian Alps: A final report to the Australian Alps Liaison
Committee, NSW National Park and Wildlife Service; McLeod, R. (2016). Cost of Pest Animals in NSW and
Australia (2016), Report prepared for the NSW Natural Resources Commission; Davies, C, Wright, W, Hogan, F
and Visintin C (2019) ‘Predicting deer-vehicle collision risk across Victoria, Australia’ Australian Mammalogy 42(3)
293-301.
Frontier Economics 24Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
o Cost to landholders of managing feral deer, such as the cost of ground shooting, fencing
the property or replacing damaged property. 35
o Competition with livestock for feed. For example, the Tallangatta Valley Landcare group
estimates that a mature feral deer eats approximately five times the amount of grass that a
mature wether eats in a year.36 When feral deer compete with livestock for their food
source farmers are forced to purchase additional fodder or reduce the stocking rate on
their farm to ensure that their stock are able to maintain weight, so they are viable to be
sold. This additional cost reduces profit margins.
o Risk of disease as feral deer can transmit diseases to livestock (e.g. cattle and sheep). While
we have not sought to value this cost, we note that the cost of an outbreak of foot and
mouth disease in Australia has been estimated to be between $6 billion and $52 billion.37
• Cost of reduced forestry production - Reports suggest that feral deer significantly reduce
the quality and total volume of timber produced by Victoria’s forestry industry, primarily as a
result of browsing and bark striping.38
• Feral deer-related vehicle accidents (including fatalities, accidents and vehicle-only
damage). The presence of feral deer in Victoria have resulted in a number of crashes and
accidents, with recent observational data suggesting that there are around 87 feral deer-
related accidents in Victoria in 2016.39
• Cost of managing feral deer by other parties (i.e. beyond the agricultural sector),
including the Victorian Government. For example, a survey by ABARES found that farm
property owners/ operators affected by feral deer spent 20 days managing feral deer on their
properties in 2019.40
• Increased cost of water supply, as a result of increased treatment requirements
(compared to a sustainable level of feral deer). While other animals are known carriers of
the parasite, Cryptosporidium sporidium, feral deer carry an increased risk as they appear in
greater abundance than other host species near Victoria’s protected water catchments.
Melbourne Water has suggested that failure to adequately control feral deer in the water
35
A survey conducted by the Invasive Species Council of North East Victorian landholders found that 42% of
respondents reported costs associated with damage to pasture, crops and trees.
36
See Submission from the Tallangatta Valley Landcare Group to Senate Inquiry on Impact of feral deer, pigs and goats
in Australia May 2021, p 5.
37
Davis et al (2016) ‘A systematic review of the impacts and management of introduced deer (family Cervidae) in
Australia’ Wildlife Research 43, 515-532, 523.
38
Ward, A, White, P, Smith, A and Critchley, C (2004) ‘Modelling the cost of roe deer browsing damage to forestry’
Forestry Ecology and Management 191, 301-310. See also; Reimoser, F, Armstrong, H, Suchant, R (1999)
‘Measuring forest damage of ungulates: what should be considered’ Forest Ecology and Management 120, 47-58.
39
https://www.theage.com.au/national/victoria/the-animal-that-causes-the-most-car-crashes-in-victoria-20160412-
go46rw.html. See also Davies, C, Wright, W, Hogan, F and Visintin C (2019) ‘Predicting deer-vehicle collision risk
across Victoria, Australia’ Australian Mammalogy 42(3) 293-301.
40
Stenekes N and Kancans, R (2021) ‘Pest animal and weed management survey 2016-19: national landholder
survey results’ Australian Bureau of Agricultural and Resource Economics and Sciences, Department of
Agriculture, Canberra 2019, 33.
Frontier Economics 25Counting the doe: an analysis of the economic, social & environmental cost of feral deer in Victoria Final
catchments, could result in the need to build costly water-treatment infrastructure to meet
water quality standards.41
Figure 7: How feral deer impact economic outcomes
Source: Frontier Economics
Given information availability and time constraints, this analysis has sought to value the most
material economic costs, namely:
• Costs to the agricultural sector, in the form of lost margin due to grazing and increased
costs to landholders of managing feral deer.
• Likelihood of feral deer-related vehicle accidents
• Lost yield in the forestry production industry
The following sections provide detail on the economic cost of feral deer, including our approach
to valuing these key costs.
Given the lack of information on the impact of feral deer on other costs, we have not been able
to robustly value the other broader economic impacts described above. As discussed below,
there is likely to be benefit of further research around the impact of feral deer to understand the
full cost of feral deer in Victoria.
41
GHD (2020), Combatting the impact of feral deer on Melbourne’s protected water catchments, available at:
https://www.ghd.com/en/perspectives/combating-the-impact-of-feral-deer-on-melbourne-s-protected-water-
catchments.aspx
Frontier Economics 26You can also read
